title: High-performance liquid chromatography/mass spectrometric identification of dibenzylbutyrolactone-type lignans: insights into electrospray ionization tandem mass spectrometric fragmentation of lign-7-eno-9,9'-lactones and application to the lignans of Linum usitatissimum L. (Common Flax).
abstract: In continuation of our studies into the mass spectrometric detection of natural lignans and their identification in complex mixtures such as crude plant extracts, the electrospray ionization tandem mass spectrometric (ESI-MS/MS) fragmentation of Delta(7,8)-unsaturated dibenzylbutyrolactone-type lignans (lign-7-eno-9,9'-lactones) was studied in detail. It is demonstrated that the characteristic fragmentation allows unambiguous identification including distinction between constitutional isomers. These lignans containing an alpha,beta-unsaturated lactone structure exist as equilibrium mixtures of E- and Z-isomers indistinguishable by mass spectrometry, but it is shown that chromatographic retention time can be used to distinguish between the isomeric forms. Based on these observations, re-analysis of the dichloromethane extract obtained from flowering aerial parts of Linum usitatissimum L. by high-performance liquid chromatography (HPLC)/ESI-MS/MS led to the identification of eighteen lignans of these types (five lignano- and one lignenolactone previously reported along with five further lignano- as well as seven lignenolactones hitherto unreported for this plant). The simultaneous identification of eighteen different lignans in the complex matrix of a crude plant extract by a single analysis demonstrates the potential of this method, which will certainly lead to new insights into the lignan composition and metabolism of different Linum species and many other plants.
authors.affiliation: Institut für Pharmazeutische Biologie und Phytochemie, Westfälische Wilhelms-Universität Münster, Münster, Germany. thomschm@uni-muenster.de
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Schmidt
authors.forename: A Wilhelm
authors.initials: AW
authors.lastname: Alfermann
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Fuss
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D019597:Flax / Q000737:chemistry*; D005663:Furans / Q000737:chemistry; D007783:Lactones / Q000737:chemistry*; D017705:Lignans / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: C439406:4,4',9-trihydroxy-3,3'-dimethoxy-9,9'-epoxylignan; D005663:Furans; D007783:Lactones; D017705:Lignans; D010936:Plant Extracts